Metallic articles are fabricated by any of a number of techniques, as may be appropriate for the nature of the metal and the article. In one common approach, metal-containing ores are refined to produce a molten metal, which is thereafter cast. The metal is refined as necessary to remove or reduce the amounts of undesirable minor elements. The composition of the refined metal may also be modified by the addition of desirable alloying elements. These refining and alloying steps may be performed during the initial melting process or after solidification and remelting. After a metal of the desired composition is produced, it may be used in the as-cast form for some alloy compositions (i.e., cast alloys), or further worked to form the metal to the desired shape for other alloy compositions (i.e., wrought alloys). In either case, further processing such as heat treating, machining, surface coating, and the like may be employed.
As applications of the metallic articles have become more demanding and as metallurgical knowledge of the interrelations between composition, structure, processing, and performance has improved, many modifications have been incorporated into the basic fabrication processing. As each performance limitation is overcome with improved processing, further performance limitations become evident and must be addressed. In some instances, performance limitations may be readily extended, and in other instances the ability to overcome the limitations is hampered by fundamental physical laws associated with the fabrication processing and the inherent properties of the metals. Each potential modification to the processing technology and its resulting performance improvement is weighed against the cost of the processing change, to determine whether it is economically acceptable.
Incremental performance improvements resulting from processing modifications are still possible in a number of areas. However, the present inventors have recognized in the work leading to the present invention that in other instances the basic fabrication approach imposes fundamental performance limitations that cannot be overcome at any reasonable cost. They have recognized a need for a departure from the conventional thinking in fabrication technology which will overcome these fundamental limitations. The present invention fulfills this need, and further provides related advantages.